I saw one in about 1990 - I was walking along a track in Wiltshire, England, near Stonehenge, and saw an orange triangle hovering above the skyline on the other side of the valley. Watched it for about 10 minutes then walked on and it had dissapeared next time I looked. I know someone else who saw the same thing so it wasn't me making it up. I also know the area really well (I grew up there) and there is nothing in the area that could explain it.